Priority is claimed based on Japanese patent application No. Hei 11-261897 filed on Sep. 16, 1999, the complete disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a paint composition containing a coloring pigment, and in particular a paint composition for forming a coating layer on a product molded from resin (hereinafter xe2x80x9ca resin molding productxe2x80x9d). The present invention is especially useful as a metallic paint that contains an inorganic coloring pigment comprising, for example, aluminum foil, although the paint composition of this invention can also be applied as a non-metallic coating containing organic pigments. Representative resin molding products to which the paint composition of this invention can be applied include bumpers, mat guards, and air bag pads for interior components, such as instrument panels and door panels.
2. Description of Related Art
Metallic coated products are predominantly adopted as side moldings for automobiles to attain aesthetic harmony between the side moldings and the sheet metal of a vehicle body exterior. Generally, the metallic coated products are made by applying a metallic paint directly onto a molded main body, with no primer layer, to form a metallic coating layer. Then, a clear coating layer comprising a clear paint is formed on the metallic coating layer. This procedure is preferred due to the high productivity that it attains.
Referring to FIG. 1, integrally molded mounts in the form of a plurality of ribs 18 are disposed on both ends of the back face of the molding main body 12 in order to press and adhere a double coated tape 20 reliably to the sheet metal of a vehicle (not shown). In FIG. 1, reference numeral 22 denotes a shiny molding piece having a decorative metal foil.
It has been found that unevenness in the surface of the molding main body 12 can cause an uneven luster to develop (typically as sink marks) in the coating film, thus adversely affecting the overall appearance of the design surface of the molding main body 12. Although the ribs 18 serve to reduce the appearance of sink marks somewhat, luster unevenness remains despite the ribs 18, particularly when the coloring pigment is an inorganic pigment.
It is an object of the present invention to provide a paint composition that can be applied to a resin molding product and a coated resin molding product to effectively color the product while reducing the luster unevenness.
In accordance with the principles of this invention, the above and other objects are attained by the provision of a paint composition for use with a resin molding product, which paint composition comprises a coloring pigment and an extender pigment present, collectively, in the paint composition at a total pigment weight concentration (PWC) of less than 30%. A paint composition satisfying these features produces a coating film having an even luster (no coating film sink marks), even when the coating film is disposed over a resin molding product having sink marks in its surface.
As referred to in this specification and the appended claims, the term xe2x80x9cPWCxe2x80x9d is an abbreviation of xe2x80x9cpigment weight concentrationxe2x80x9d and means the total weight of the pigments of the paint based on the total weight of the solid ingredients of the paint (coating film).
In the embodiment described above, the paint composition is particularly effective (even in small amounts) in reducing luster unevenness in the coating film where an inorganic pigment is selected as the coloring pigment, and silica (silicon dioxide) or talc (magnesium silicate), especially silica, is selected as the extender pigment.
Additional objects of this invention include the provision of a coated resin molding product comprising a resin molding product coated with a coating film prepared from the paint composition, and the provision of a method for use of the paint composition to create a coating layer on a resin molding product.